QrCodeDrawing.cs

//
// QR code generator library (.NET)
// https://github.com/manuelbl/QrCodeGenerator
//
// Copyright (c) 2021 Manuel Bleichenbacher
// Licensed under MIT License
// https://opensource.org/licenses/MIT
//

using System.Windows;
using System.Windows.Media;
using System.Windows.Media.Imaging;

namespace Net.Codecrete.QrCodeGenerator.Demo
{
    public class QrCodeDrawing
    {
        /// <summary>
        /// Create a resolution independent drawing for the specified QR code.
        /// <para>
        /// The drawing can be used as an image's source, or for printing.
        /// </para>
        /// </summary>
        /// <param name="qrCode">The QR code.</param>
        /// <param name="size">The width and height of the resulting drawing, including the border (in dip).</param>
        /// <param name="borderWidth">The width of the border, in multiples of a single module (QR code pixel)</param>
        /// <returns>The device independent drawing.</returns>
        public static DrawingImage CreateDrawing(QrCode qrCode, double size, int borderWidth = 3)
        {
            return CreateDrawing(qrCode, size, borderWidth, Colors.Black, Colors.White);
        }

        /// <inheritdoc cref="CreateDrawing(QrCode, double, int)"/>
        /// <param name="foreground"></param>
        /// <param name="background"></param>
        /// <returns>The device independent drawing.</returns>
        public static DrawingImage CreateDrawing(QrCode qrCode, double size, int borderWidth, Color foreground, Color? background)
        {
            var group = new DrawingGroup();
            using (var drawingContext = group.Open())
            {
                var backgroundBrush = background != null ? new SolidColorBrush((Color)background) : null;
                var foregroundBrush = new SolidColorBrush(foreground);
                double scale = size / (qrCode.Size + 2 * borderWidth);
                drawingContext.PushTransform(new ScaleTransform(scale, scale));
                Draw(qrCode, drawingContext, borderWidth, foregroundBrush, backgroundBrush);
                drawingContext.Pop();
            }

            var image = new DrawingImage(group);
            image.Freeze();
            return image;
        }

        /// <summary>
        /// Draws the QR code in the specified drawing context.
        /// <para>
        /// The QR code is drawn with the top left corner of the border at (0, 0).
        /// Each module (QR code pixel) will be drawn with 1 unit wide and tall.
        /// If a different position or size is desired, the drawing context's transformation
        /// matrix can be setup accordingly.
        /// </para>
        /// </summary>
        /// <param name="qrCode">The QR code.</param>
        /// <param name="drawingContext">The drawing context.</param>
        /// <param name="borderWidth"></param>
        /// <param name="foreground"></param>
        /// <param name="background"></param>
        public static void Draw(QrCode qrCode, DrawingContext drawingContext, int borderWidth, Brush foreground, Brush? background)
        {
            int size = qrCode.Size;

            // draw the background
            if (background != null)
            {
                drawingContext.DrawRectangle(background, null, new Rect(0, 0, size + 2 * borderWidth, size + 2 * borderWidth));
            }

            // draw the modules
            for (int y = 0; y < size; y++)
            {
                for (int x = 0; x < size; x++)
                {
                    if (qrCode.GetModule(x, y))
                    {
                        var rect = new Rect(x + borderWidth, y + borderWidth, 1, 1);
                        drawingContext.DrawRectangle(foreground, null, rect);
                    }
                }
            }
        }

        /// <summary>
        /// Create a bitmap for the specified QR code.
        /// <para>
        /// To achieve a crisp bitmap without any anti-aliasing, the bitmap is sized such
        /// that each QR code module is multiple pixels tall and wide.
        /// The resulting size depends on the QR code size;
        /// it is (qr-code-size + 2 * border-width) pixels tall and wide.
        /// </para>
        /// </summary>
        /// <param name="qrCode">The QR code.</param>
        /// <param name="moduleSize">The size of each module (QR code pixel), in pixels</param>
        /// <param name="borderWidth">The width of the border around the QR code, in multiples of a single module (QR code pixel).</param>
        /// <returns>The bitmap.</returns>
        public static BitmapSource CreateBitmapImage(QrCode qrCode, int moduleSize, int borderWidth = 3)
        {
            return CreateBitmapImage(qrCode, moduleSize, borderWidth, Colors.Black, Colors.White);
        }

        /// <inheritdoc cref="CreateBitmapImage(QrCode, int, int)"/>
        /// <param name="foreground">The forground color.</param>
        /// <param name="background">The background color.</param>
        /// <returns>The bitmap.</returns>
        public static BitmapSource CreateBitmapImage(QrCode qrCode, int moduleSize, int borderWidth, Color foreground, Color background)
        {
            var drawingVisual = new AliasedDrawingVisual();
            int size = qrCode.Size + 2 * borderWidth;

            using (var drawingContext = drawingVisual.RenderOpen())
            {
                var foregroundBrush = new SolidColorBrush(foreground);
                var backgroundBrush = new SolidColorBrush(background);
                drawingContext.PushTransform(new ScaleTransform(moduleSize, moduleSize));
                drawingContext.DrawRectangle(backgroundBrush, null, new Rect(0, 0, size, size));
                Draw(qrCode, drawingContext, borderWidth, foregroundBrush, null);
            }

            var bitmap = new RenderTargetBitmap(size * moduleSize, size * moduleSize, 96, 96, PixelFormats.Pbgra32);
            bitmap.Render(drawingVisual);
            return bitmap;
        }

        /// <summary>
        /// Drawing visual using aliased edge mode.
        /// <para>
        /// This subclass is needed because the <c>VisualEdgeMode</c> property is protected
        /// and <see cref="RenderOptions"/> doesn't work for <c>DrawingVisual</c>.
        /// </para>
        /// </summary>
        class AliasedDrawingVisual : DrawingVisual
        {
            public AliasedDrawingVisual()
            {
                VisualEdgeMode = EdgeMode.Aliased;
            }
        }

    }
}